something similar happened on a old CRT TV i had a long time ago. I used it for about 4 years, then the picture went all crazy. For 1 week, the picture would be displayed for some thme (about 30 secs), then the screen was off ( blank ) for about 30 secs. Finally, the screen just went all blank. While this was happening, the sound was alright. Now, the TV is taken apart by me, I salvaged a lot of parts from it

I have no clue why this happens? anyone knows what might cause this?
I also have a old computer, and there's a problem with the CRT moniter's display. Most of the time, the screen is stretched , the left + right part of the screen would be cut-off. A pin was missing from the VGA connecter, but the funny thing about this is 80% of the time when I press hard on the sides, or top of the moniter or just bang it, the screen on the moniter would fit the screen and not be stretched for a few seconds, to a few minutes. Now its just abandoned.
Weird, if anyone knows why this happened, its appreciated